The present invention relates to memory controllers or memory components comprising an adjustable transmitter impedance, memory arrangements comprising such memory controllers and corresponding methods.
In memory arrangements, usually a memory controller communicates with one or more memory components, for example memory chips. As an example, if data is to be written to the memory arrangement, the memory controller receives a corresponding write request, for example from a microprocessor, and then sends a write command together with the data to be written to one or more of the memory components. To achieve this, one or more communication lines, for example connections on a printed circuit board, need to be provided between the memory controller and the memory components.
In case a transmitter impedance of a transmitter of the memory controller sending data and/or commands is not correctly matched with an impedance of the communication lines, reflections may occur which distort the signal form at a receiver in the memory components and which may lead to incorrect writing of data.
Therefore, in some systems a variable transmitter impedance is provided at the transmitter which is calibrated using for example an external precise reference resistor. To be able to couple the reference resistor with the variable transmitter impedance, a dedicated pin of a package of the memory controller is conventionally necessary, which is undesirable due to cost and space restraints.
A different approach is to measure the transmitter impedance during a production test and to provide a correction value for each memory controller manufactured, which may be written into a non-volatile memory of the memory controller, for example a so-called eFuse. Such eFuse requires silicon area and testing time during the production test, both of which is also not desirable.